This invention relates to disposable absorbent products for absorbing body fluids and, in particular, to sanitary napkins adapted to be worn against the perineal region of the body and held in place in the crotch portion of the undergarment when worn by the user. In a specific non-limiting example of the inventive principle, the sanitary napkin is provided with a pair of stiff flaps that are associated to the longitudinal sides of the sanitary napkin and cause the sides to bend upwardly as they are parted during placement of the sanitary napkin on the undergarment of the wearer. The upwardly bent sides form upstanding barriers that impede body exudate discharged on the sanitary napkin from leaking past the sides of the sanitary napkin.
Sanitary napkins are prone to fail when body exudate is discharged on the napkin at a higher rate than that which the napkin can take up. When such failure occurs, body exudate usually leaks at the sides of the sanitary napkin and soils the undergarment.
One approach to solve this problem has been described in the international patent application PCT/SE91/00735 filed on Oct. 31, 1991 and published on May 14, 1992 which teaches a sanitary napkin with side flaps that in use are folded over the edges of the crotch portion of the undergarment. A portion of each side flap is bonded in a face-to-face relationship with the flange seal of the sanitary napkin that surrounds the absorbent system. When the napkin is worn, the side flaps are pulled out from the sides of the central absorbent pad causing flange seal to raise into an upstanding barrier. However, in practice, the upstanding barrier may not always be created. For example, if the width of the central absorbent pad is not substantially less than the width of the user""s undergarment, it will not be possible for the flaps to be pulled and maintained in an outward orientation with respect to the absorbent pad. If the flaps are not maintained in this position, the upstanding barrier will not be formed.
Against this background, there exists a need in the industry to provide a sanitary napkin that offers a reduced likelihood of side failure.
In accordance with the present invention, there has been provided a sanitary napkin having a main body including at least three superposed functional layers, namely a fluid permeable body facing layer, an absorbent layer and a liquid impermeable undergarment facing layer. The main body has a pair of opposite longitudinal sides and a pair of opposite transverse sides. The sanitary napkin has at least one flap that is affixed to or otherwise physically associated with each longitudinal side of the main body. The flap is characterized as having a rigidity that is sufficient to cause the longitudinal side to fold upwardly when the flap is subjected to an effort causing outward displacement of the flap from a first position toward a second position, in the first position the flap acquiring a more acute angular relationship to the liquid impermeable undergarment facing layer than in the second position.
One benefit of this sanitary napkin is the formation of an upstanding barrier on the main body that impedes the lateral flow of body exudate and can, therefore, reduce the likelihood of failures. The upstanding barrier results from the outward displacement of the flap that is normally effected when the sanitary napkin is installed on the undergarment of the wearer. The longitudinal side of the main body is maintained in the upwardly oriented position during the use of the sanitary napkin since the flap is restrained from moving back toward the liquid impermeable undergarment facing layer by the undergarment.
Optionally, the main body is manufactured such that the longitudinal side has a resiliency sufficient to urge the flap into mechanical engagement with the crotch portion of the undergarment when the effort causing outward displacement of the flap from the first position toward the second position ceases.
Another option is to provide the sanitary napkin with a pair of stiff flaps, each flap being associated with a respective longitudinal side. The upstanding barriers on the main body are formed when the flaps are parted to install the sanitary napkin on the crotch portion of the undergarment and they are maintained in this position during the use of the sanitary napkin.
In a specific non-limiting example of implementation, the main body is generally rectangular with substantially rounded ends. When the main body is of such a conformation, the transverse sides are the shorter opposing sides and will generally have an arcuate shape. The longitudinal sides are the longer opposing sides and will generally be arcuate, typically inwardly arcuate. It should be understood, however, that the shape of such sides is not essential to the invention, and thus the transverse or the longitudinal sides could either be arcuate or straight.
The main body is of a laminate construction and has at least three functional layers, namely: the fluid permeable body facing layer, the absorbent layer and a liquid impermeable undergarment facing layer. The fluid permeable body-facing layer is usually designated as xe2x80x9ccover layerxe2x80x9d. The cover layer is fluid-permeable, and thus will permit the body exudate discharged on the main body to pass through it and into the layers below.
The absorbent layer underlies the cover layer and is often referred to as an xe2x80x9cabsorbent systemxe2x80x9d. The absorbent layer may comprise a single layer or a composite layer combining multiple layers or additional structures; the primary purpose of all of which being to absorb and retain body exudate. Many different absorbent systems are known in the art.
Underneath the absorbent system is the liquid impermeable undergarment-facing layer, also called xe2x80x9cbarrier layerxe2x80x9d. The primary purpose of the barrier layer is to prevent exudate absorbed within the sanitary napkin from egressing the sanitary napkin on the opposite side from which it was absorbed. The barrier layer is thus impervious to liquid but could be made pervious to gases to provide breathability.
The cover layer and the barrier layer are joined to one another around the periphery of the sanitary napkin to form a flange seal enclosing the absorbent system, and thus forming a structurally integral sanitary napkin. Other conventional methods of adhering or uniting the various components of the article together, such as adhesive between the components, are all also within the scope of the present invention.
The sanitary napkin has a pair of flaps each flap affixed to a respective opposite longitudinal side of the main body. Each flap has a proximal end portion and a distal end portion. The proximal end portion is the portion of the flap that is physically attached to the main body while the distal end portion is the opposite end portion of the flap that is remote from the main body. Each flap is attached to a portion of the flange seal that forms a respective longitudinal side of the main body. More specifically, the surface of the flap that faces the barrier layer is attached in a face to face relationship to the lower surface of the flange seal (the surface of the flange seal that is oriented toward the undergarment of the wearer).
At least a portion of each flap is constructed of a material that is sufficiently rigid such that when the flaps are parted to allow the sanitary napkin to be installed on the crotch portion of the undergarment, they will raise the flange seal to form a pair of opposite upstanding barriers. The stiffness or rigidity of the flaps should be sufficient to cause the flange seal to fold upwardly when the flaps are parted. In general, the more rigid the flange seal, the stiffer the flaps should be. In a specific example, the flaps are formed from a foam material. Alternatively, the flaps can be formed of a material that is not inherently rigid but to which rigidity has been imparted by specific treatments or by addition of specific structures. One specific treatment to impart or enhance rigidity is embossing. Embossing has the effect of densifying the material and thus renders it less pliable. Alternatively, specific structures such as additional layers of material can be added to reinforce the tab.